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Ants Adjust Foraging So the Colony Eats Right

For most creatures, eating right is a solitary pursuit. But how do social insects, for whom relatively few members of the group are responsible for the food supply, maintain the appropriate levels of nutrients for everyone? In a study of green-headed ants, Audrey Dussutour and Stephen J. Simpson of the University of Sydney in Australia provide an answer. The foragers of the colony, they report in Current Biology, adjust their food collection and nutrient processing as the situation demands.

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Chris Gash

The researchers provided colonies with a choice of two foods with complementary proportions of protein and carbohydrate. They found that in colonies with larvae, foragers were able to maintain consistent levels of protein and carbohydrate no matter what the choices were, and that the level of protein was higher than in colonies without larvae. “Ants are able to listen to the nutritional need of the larvae,” which need more protein, said Dr. Dussutour, now at Paul Sabatier University in France.

The researchers then forced colonies to consume unbalanced diets. In colonies with larvae, if the food was low in protein the ants would collect more of it to maintain a certain level of protein. Conversely, they would collect less high-protein food.

But the researchers also found that the foragers were removing excess protein, discarding it after digesting the carbohydrates in the food. Over all, Dr. Dussutour said, the colony acts as a collective mouth and gut, manipulating the available nutrients.

A version of this article appears in print on , on Page D3 of the New York edition with the headline: Ants Adjust Foraging So the Colony Eats Right. Order Reprints|Today's Paper|Subscribe